Hi again!

Sorry for posting my image here! I canceled my post and will post a link to 
a website.

Here my question again:


I'm very new to POV-Ray and use Blender to create my scenes. There's a nice 
export tool available and it works good so far but it seems that there's 
something wrong with POV-Rays way to handle uv-mapping. In Blender it looks 
okay but POV-Rays version looks very ugly. It's to grey and even when I 
increase the ambient value it looks pretty bad. There are also some 
distortions on the shelf I can't explane. What can I do to increase the 
quality of my image?

Okay, now you can find my example here:

http://320002096658-0001.bei.t-online.de/example.jpg

Again, sorry for my mistake,

Andreas

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Firstly, you should try adding this line at the beginning of the pov file
you are rendering:

global_settings { assumed_gamma 1 }

  (For one reason or another the default assumed_gamma is so that colors
will have visibly less saturation than their values would imply. AFAIK
assumed_gamma 1 will make povray to take the colors unmodified.)

  Secondly, you should make sure that the exporting tool you are using
is really outputting the correct UV information for povray. Of course
this is just a shot in the dark, but it could explain wrongly-mapped
textures.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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"Warp" wrote:
>
>   (For one reason or another the default assumed_gamma is so that colors
> will have visibly less saturation than their values would imply. AFAIK
> assumed_gamma 1 will make povray to take the colors unmodified.)

AFAIK not specifying assumed_gamma results in no gamma correction. So there
isn't really a default.
When you use assumed_gamma 1 the colors get actually less saturated but only
for Display_gamma > 1.

Post a reply to this message

3da04595@news.povray.org...
> I'm very new to POV-Ray and use Blender to create my scenes. There's a
nice
> export tool available and it works good so far but it seems that there's
> something wrong with POV-Rays way to handle uv-mapping. In Blender it
looks
> okay but POV-Rays version looks very ugly. It's to grey and even when I
> increase the ambient value it looks pretty bad. There are also some
> distortions on the shelf I can't explane. What can I do to increase the
> quality of my image?

The only way to know is to look at the exact texture definition provided by
the converter and see if it makes sense in POV-Ray. Converters often have
very bizarre ways to create POV-Ray textures and I never use their texture
output directly. For some reason, for instance, some converters insist in
creating texture layers that only mess up the texture code. It could really
be anything... and nothing serious unless the uv-mapping is actually wrong
(this you can check by replacing the texture map with a checker pigment).

G.


--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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This isn't a texture problem, it's a shadow problem. The textures are
appearing *slightly* different shades, but the "artifacts" you're talking
about aren't really artifacts.

It looks to me like Blender was using a soft-shadow light, and when it
exported, it put a point light in POV-Ray. look up "area_light" in POV-Ray's
documentation and make the light_source an area light. That will blur the
shadows of the blinds and the plant and make things look more like they did
in blender.

All those dark parts are just shadows from the blinds and from the plant.

Now that I look more closely, I don't see any shadows in Blender at *all*
from anything *but* the blinds. If you want only the blinds to cast shadows,
then put the no_shadow flag in every other object.

 - Slime
[ http://www.slimeland.com/ ]

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Gilles Tran wrote:

> The only way to know is to look at the exact texture definition provided
> by the converter and see if it makes sense in POV-Ray. Converters often
> have very bizarre ways to create POV-Ray textures and I never use their
> texture output directly. For some reason, for instance, some converters
> insist in creating texture layers that only mess up the texture code. It
> could really be anything... and nothing serious unless the uv-mapping is
> actually wrong (this you can check by replacing the texture map with a
> checker pigment).

Hi,

Warp advised me to add a "global_settings { assumed_gamma 1 }" statement. 
Indeed, the picture is brighter now and looks better. No I can see, that 
the uv-mapping is okay, but the colors are bad. It looks like a baloon that 
you blow up to much and the skin will get to thin, although the texture is 
very large (700x450 pixel) and the object itself is comparatively small.

Is it possible that the pigment colors influence the texture?
This is the corresponding code block:

-------------------------------------------------------
#declare ma_book1_pig=pigment{color rgb <1.0,1.0,1.0> }

#declare ma_book1_fsh=finish {
                
//              ambient 0.6
                diffuse 0.1953125
                specular 0.25 roughness 0.8046875
}
-------------------------------------------------------

And here is a second sample file with correct gamma but still ugly colors:

http://320002096658-0001.bei.t-online.de/example2.jpg


Thanks for help,
Andreas

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Slime wrote:

> It looks to me like Blender was using a soft-shadow light, and when it
> exported, it put a point light in POV-Ray. look up "area_light" in
> POV-Ray's documentation and make the light_source an area light. That will
> blur the shadows of the blinds and the plant and make things look more
> like they did in blender.

Blenders render engine is rather poor. It doesn't support real soft 
shadows. It creates shadow maps or layers of shadow maps that looks like 
smooth. The blured (and not very good looking) shadows are the result of 
low filter settings (shadow map buffersize, samples etc.)

> All those dark parts are just shadows from the blinds and from the plant.
> 
> Now that I look more closely, I don't see any shadows in Blender at *all*
> from anything *but* the blinds. If you want only the blinds to cast
> shadows, then put the no_shadow flag in every other object.

No, I don't want only the blinds to cast shadows. As I said before, 
sometimes Blender is not very exactly in calculate shadows (respectively 
light rays) - it's not a ray tracer and that's the reason why I want to use 
POV-Ray :-)

BTW: I'm not sure whether I should use area lights. In my scene the sun 
shines directly through the window and passes the blinds. This should cast 
sharp shadows, shouldn't it?

Thanks,
Andreas

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> BTW: I'm not sure whether I should use area lights. In my scene the sun
> shines directly through the window and passes the blinds. This should cast
> sharp shadows, shouldn't it?

In real life, the sun casts soft shadows. This is because it's not a single
point in space; it's a sphere that has a definite size. So make an area
light that has the same size as the sun.

Well, not really. Since your light source surely isn't as far away as the
sun really is, you don't want it to be that big. But estimate so that it
would *look* the same as the sun does from where the camera is.

 - Slime
[ http://www.slimeland.com/ ]

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3da07bdc@news.povray.org...

> #declare ma_book1_fsh=finish {
>
> //              ambient 0.6
>                 diffuse 0.1953125
>                 specular 0.25 roughness 0.8046875


That's what I said, for some reason converters create funky texture
statements...
ambient 0.6 diffuse 0.16 doesn't make much sense (only for special effects
or very particular situations)
As a rule, for usual opaque materials, ambient values should be kept low (0
the better, particularly with radiosity) and diffuse values kept high (1
works in most cases and can be lowered if necessary).

G.


--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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